1. Field of the Invention
The invention relates generally to switches and more particularly to electromechanical multiposition rotary switches and to a method of manufacturing rotary switches.
2. Description of Related Art
As compared to many other types of electrical switching mechanisms, the electromechanical rotary switch provides a desirable means to control large numbers of circuits over a wide range of currents, voltages and power requirements. Rotary style switches provide electrical control for instrumentation, medical equipment, aircraft, computers, industrial controls, communication, ordnance, as well as ground support equipment.
Conventional rotary switches include a cylindrically shaped metal housing with an integral ferrule fabricated into one end of the housing. A rotor mounted within the metal housing is coupled to a shaft which extends through the ferrule such that the shaft can be manipulated and rotated by the fingers of an operator's hand. The metal housing also contains a stator mounted at the other end thereof adjacent to the rotor. The stator typically has an arrangement of stationary terminals and common contacts thereon. An arrangement of contact springs and metallic balls and brush contacts located on the rotor slidably and selectively engage certain of the terminals or contacts on the stator. More specifically, metal contacts associated with terminals or common contacts located on the stator are selectively electrically coupled to various other terminals or common contacts on the stator by turning the shaft and the rotor therewith.
Disadvantageously, the metal housing arrangement described above is labor intensive to fabricate requiring a number of intricate machining operations to complete, which is especially problematic for smaller switch sizes. Additionally, where the metal housing is used to engage the rotor detent mechanism, wear of the internal surface of the metal housing over time will produce tiny metal fragments. Such fragments may become lodged on the surface of the stator and cause undesirable shorting between the electrical contacts thereon. A plastic sleeve inside of the metal housing may be used for indexing purposes to substantially reduce the shorting problem. However, such sleeve increases the overall diameter of the switch and adds to the manufacturing cost . A rotary switch without these aforementioned problems and other undesirable features would provide an advancement in the art.